There has been tremendous increase in last few years in the development of cancer vaccines with Tumour-associated antigens (TAAs) due to the great advances in identification of molecules based on the expression profiling on primary tumours and normal cells with the help of several techniques such as high density microarray, SEREX, immunohistochemistry (IHC), RT-PCR, in-situ hybridization (ISH) and laser capture microscopy (Rosenberg, Immunity, 1999; Sgroi et al, 1999, Schena et al, 1995, Offringa et al, 2000). The TAAs are antigens expressed or over-expressed by tumour cells and could be specific to one or several tumours for example CEA antigen is expressed in colorectal, breast and lung cancers. Sgroi et al (1999) identified several genes differentially expressed in invasive and metastatic carcinoma cells with combined use of laser capture microdissection and cDNA microarrays. Several delivery systems like DNA or viruses could be used for therapeutic vaccination against human cancers (Bonnet et al, 2000) and can elicit immune responses and also break immune tolerance against TAAs. Tumour cells can be rendered more immunogenic by inserting transgenes encoding T cell co-stimulatory molecules such as B7.1 or cytokines IFNgamma, IL2, GM-CSF etc. Co-expression of a TAA and a cytokine or a co-stimulatory molecule can develop effective therapeutic vaccine (Hodge et al, 95, Bronte et al, 1995, Chamberlain et al, 1996).
There is a need in the art for reagents and methodologies useful in stimulating an immune response to prevent or treat cancers. The present inventions provides such reagents and methodologies which overcome many of the difficulties encountered by others in attempting to treat cancers such as cancer. In particular, the present invention provides a novel coding sequence for CEA. This nucleotide sequence, CEA(6D)-1,2, includes sequence modifications that eliminate the expression of truncated forms of CEA as expressed from expression vectors. Such a modified sequence is desired by those of skill in the art to improve expression and immunization protocols for CEA.